Reserves space for an item of <size> bytes on the queue but doesn't fill the content. The caller is expected to fill in the content using the returned slice.
size of the space of the item that should be reserved
slice to the reserved space if it was successfully reserved, else null
See Implementation
Reserves space for an item of <size> bytes on the queue but doesn't fill the content. The caller is expected to fill in the content using the returned slice.